In April 1987 a study was begun to evaluate two approaches to the prevention of gingivitis in teenage children. Baseline examinations for periodontal health (plaque, pocket depth, calculus, gingival bleeding), DMFS and gingival recession were conducted on 500 ninth and tenth graders in the York Country High Schools, Virginia. Questionnaires regarding oral hygiene methods and professional care practices were completed by each student. Following the examinations, subjects were randomly assigned by grade to either a positive control or test group. The control group received a manual for the self-assessment and control of plaque and the test groups received a manual for the self-assessment and control of gingival bleeding. Every subject participated in small group sessions for instruction in the self- assessment procedures and supply distribution. Two weeks later, individual instruction was held to ensure that the procedures were understood. Examinations of periodontal health will be conducted in October and April of the next two school years. DMFS and gingival recession examinations will be repeated at the final examination in April 1989. Each participant will receive an oral prophylaxis in May 1988.